Baltimore Checkerspot
Euphydryas phaeton (Drury, 1773)

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Diagnosis: The Baltimore Checkerspot is unique in appearance in eastern North America. The upperside is black with a row of orange crescents along the outer edge of the wings. There are several rows of white spots inside the orange crescents. The underside is similar with larger white spots. The females can be quite large. Wingspan: 44 to 70 mm.

Subspecies: Only the nominate subspecies is found in Canada.

Range: This is a butterfly of the eastern U.S. and southeastern Canada. In the Maritimes, it is found in Nova Scotia north to Baddeck on Cape Breton Island, west through Prince Edward Island and New Brunswick, along the St. Lawrence River Valley in Quebec, and throughout southern Ontario north to Algonquin Provincial Park. There are isolated records from Sault Ste. Marie and Lake Nipigon, in northern Ontario, and a few records from southeastern Manitoba.

Similar Species: None in eastern North America.

Baltimore Checkerspot (Euphydryas phaeton phaeton), larva. W. Lukey).

Early Stages: Large masses of eggs are laid under the leaves of the preferred foodplant Turtlehead (Chelone glabra). The larvae are black with branching spines, with orange stripes crossing the body. They feed communally in a silken nest until August, when they make the nest more compact and remain quiescent until October. They then descend as a group to the ground and split into smaller groups, constructing hibernating webs containing leaves and other debris (Bowers, 1978). In the spring they will sometimes feed on other plants; ash (Fraxinus spp.) seems to be a preferred alternate foodplant in Ontario.

Baltimore Checkerspots (Euphydryas phaeton phaeton), mating. Ottawa, Ont. J.D. Lafontaine

Abundance: The Baltimore Checkerspot is very localized to the vicinity of the foodplant Turtlehead and rarely strays. It can be common in some favoured locales.

Flight Season: It flies from mid-June to early August in its Canadian range.

Habits: This is a butterfly of wet meadows and marshes in Canada. It is a relatively weak flier and can be followed closely as it remains near the ground and alights frequently on vegetation.

© 2002. This material is reproduced with permission from The Butterflies of Canada by Ross A. Layberry, Peter W. Hall, and J. Donald Lafontaine. University of Toronto Press; 1998. Specimen photos courtesy of John T. Fowler.

The Toronto Entomologists' Association thanks Agriculture and Agri-Food Canada for providing the content and computer code for this web page.